1. Field of the Invention
The present invention relates to a printer for generating a color image on recording material by a thermal head or a laser head using an ink ribbon, and particularly relates to a method of preventing dust from adhering to an ink ribbon and a printer.
2. Description of the Related Art
In a printer for recording an image and data by a thermal head, a laser head and others, dust adhering to recording material and others may have a serious effect upon the quality of a finished image, particularly a finished color image.
For example, as shown in FIG. 9, in a printer adopting a method of bonding a toner sheet T and an image receiving sheet R, heating them using a laser head and transferring an image generated by peeling developing from the toner sheet T to the image receiving sheet R, if dust X exists on the toner sheet T, the energy of a laser beam L for recording is attenuated or intercepted, a part in which the dust X exists is not recorded, a white dot is made, an image is thinned, the density is deteriorated and the unevenness of an image is caused.
Also, as shown in FIG. 10, in a printer adopting a method of bonding a toner sheet T and an image receiving sheet R, heating them using a thermal head TH and transferring an image generated by peeling developing from the toner sheet T to the image receiving sheet R, if dust X exists on the toner sheet T, the transmitted quantity of thermal energy from the thermal head TH to a record medium (T and R) is attenuated or intercepted in a part in which the dust X exists, the part is not recorded, a white dot or a white stripe is made, an image is thinned, the density is deteriorated and the unevenness of an image is caused.
An arrow C shows a direction in which the toner sheet T and the image receiving sheet R are moved for the thermal head.
Heretofore, to remove dust which adheres to a toner sheet and causes the above problems, an adhesive roller is arranged between the toner sheet and a laser head or a thermal head and the dust on the toner sheet has been removed by the adhesive roller.
Hereby, the dust on the toner sheet can be removed by the adhesive roller to some extent before the above laser head or thermal head. However, if a toner sheet is electrified for any reason or dust itself is electrified, it is difficult to completely remove the dust even if the adhesive roller is used. There is a problem that the provision of the adhesive roller results in the increase of the cost of a device and it troubles an operator to keep the adhesive roller a satisfactory state.
The object of the present invention is to basically solve the above problems in prior art and to provide a method of preventing dust from adhering to a toner sheet and such a printer.
To achieve the above object, in this invention, the following part of an ink ribbon is rewound in a direction in which the ribbon is let out so that dust is prevented from adhering to a part used for next printing of the ink ribbon after setting of the ink ribbon and/or every termination of printing.
In this invention, if an ink ribbon is rewound after setting the ink ribbon, the ink ribbon which has no room to be rewound is kept as it is and the ink ribbon is idly let out to the next printing start position when first printing is started.
Further, in this invention, means for automatically rewinding the ink ribbon by a predetermined length after setting the ink ribbon and/or every termination of printing is provided.
In this invention, the above predetermined length is equivalent to the length of one image plane or shorter.
Further, in this invention, means for automatically letting out an ink ribbon by a length which was rewound formerly when the next printing is started, is provided.
As described above, in this invention, as the part actually to be used is separated from a carrier, in which dust readily adheres, until an ink ribbon is used, the probability of adhering dust to the part actually to be used becomes lower. Hereby, the unevenness of an image and the deterioration of the quality of an image, which are respectively caused by a thinned image, the lower density and others, can be prevented without increasing the cost of the device and without troubling an operator.